Background: Small modular reactors, explained: who is building them worldwide · Every Nuclear Plant Under Construction in the US in 2026
Current state
| Status | Planned |
| Design | Xe-100 (HTGR, SMR) |
| Net capacity | 80 MWe |
| Country | United States |
| Vendor | X-energy |
| Owner / operator | Long Mott Energy (Dow) |
| Construction start | — |
| Original COD target | — |
| Current COD estimate | — |
| Schedule slippage | — |
Notes
One of four Xe-100 modules (80 MWe each, per the NRC) planned to supply electricity and process steam to Dow's Seadrift Operations, with DOE Advanced Reactor Demonstration Program support. The NRC construction permit decision is pending: the NRC project page (updated 2026-09-14) targets the final safety evaluation for November 2026 and lists the hearing and permit decision as not yet scheduled. A licensing board admitted the San Antonio Bay Estuarine Waterkeeper as intervenor in January 2026. No construction start or in-service date has been announced.
Milestone log
- 2025-03-31 — Long Mott Energy, a wholly-owned Dow subsidiary, filed a construction permit application with the NRC for a four-module Xe-100 plant (320 MWe) at Seadrift, Texas (source)
- 2025-05-12 — NRC completed its acceptance review and docketed the construction permit application (source)
- 2026-05-18 — NRC issued the environmental assessment and finding of no significant impact for the project, ahead of schedule (source)
The milestone log is append-only: corrections are recorded as new entries, never rewrites. Full history via /api/v1/changes.
NNN coverage
On the Xe-100 design
- UK opens Xe-100 design assessment, first HTGR in GDA pipeline 2026-09-16
- X-energy and Centrus sign HALEU deal for Xe-100 2026-08-07
- Nuclear power for data centers, explained: every deal tracked 2026-10-01
- The 6 nuclear stories that mattered this week 2026-09-19
- Cameco signs exclusive offtake for all Paducah laser-enrichment output 2026-09-14
- HALEU, explained: the fuel advanced reactors need 2026-08-27
Sources
- https://www.nrc.gov/reactors/new-reactors/advanced/who-were-working-with/applicant-projects/long-mott
- https://www.ans.org/news/2026-02-20/article-7771/nrc-board-to-hear-challenges-to-dows-long-mott-application/
- https://x-energy.com/news/nrc-issues-environmental-assessment-with-finding-of-no-significant-impact-for-dow-and-x-energys-propsed-advanced-nuclear-project-in-texas/
- https://x-energy.com/media/news-releases/nrc-publishes-18-month-review-schedule-for-xe-100-construction-permit-application